Liquid pump of screw expander

ABSTRACT

A liquid pump of a screw expander is disclosed, applicable to an Organic Rankin Cycle (ORC). The liquid pump of a screw expander includes a semi-sealed or fully sealed shell. An expander unit and a liquid pump unit are disposed in the shell. The expander unit includes a screw rotor, and the liquid pump unit includes a screw rotor. The rotor of the expander unit is fixedly connected to the rotor of the liquid pump unit. The rotor of the liquid pump unit rotates under driving of the rotor of the expander unit. In the liquid pump of a screw expander applied to the ORC, since a resistance torque of the female rotor is small, the liquid pump does not wear even when the liquid viscosity is low, contributing to high reliability of the liquid pump. Meanwhile, the liquid pump is driven by the screw expander, thereby further improving power generation efficiency of the ORC. In addition, the semi-sealed or fully sealed shell can effectively prevent leakage of a refrigerant

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to the field of Organic Rankin Cycle (ORC)technology, specifically to an ORC power generation system, and morespecifically to a liquid pump of a screw expander of the ORC powergeneration system.

2. Description of Related Arts

Referring to FIG. 1, FIG. 1 is a typical ORC, which includes an expander1′, a generator 2′, an evaporator 3′, a liquid pump 4′ and a condenser5′.

A low-temperature and low-pressure liquid refrigerant is pressurized inthe liquid pump 4′, and then enters the evaporator 3′ to be evaporatedthrough heating until the refrigerant becomes an overheated gas (hightemperature and high pressure). The overheated gas enters the expander1′ to work through expansion, so as to drive the generator 2′ togenerate power. After working, the low-temperature and low-pressure gasenters the condenser 5′ and is condensed to liquid, and then flows backinto the liquid pump 4′, thus completing a cycle.

Most of the existing liquid pumps are open-type gear pumps orcentrifugal pumps. The gear pump has the following defects: in the gearpump, one gear always drives another gear, and half of the consumed workis consumed during a driving process; meanwhile, in the ORC cycle,liquid viscosity is usually low, and the gear wears easily. Thecentrifugal pump has the following defect: after the centrifugal pumpsucks the liquid, a pressure during the suction process is decreased,and the liquid evaporates easily, which causes efficiency of thecentrifugal pump to decrease, thereby affecting efficiency of the entireORC cycle. The open-type liquid pump has the following defect: therefrigerant leaks easily through a shaft seal.

In addition, power generation efficiency of the ORC power generationsystem is low; moreover, the existing gear pump or centrifugal pump isdriven by a motor, which consumes power, thereby further decreasing thepower generation efficiency of the ORC power generation system.

SUMMARY OF THE PRESENT INVENTION

The technical problem to be solved by the present invention is toprovide a liquid pump of a screw expander, which is capable of improvingreliability of the liquid pump.

In order to solve the above technical problem, the present inventionadopts the following technical solution.

A liquid pump of a screw expander is provided, comprising a semi-sealedor fully sealed shell, wherein an expander unit and a liquid pump unitare disposed in the shell; the expander unit comprises a screw rotor,and the liquid pump unit comprises a screw rotor; the rotor of theexpander unit is fixedly connected to the rotor of the liquid pump unit,and the rotor of the liquid pump unit rotates under driving of the rotorof the expander unit.

As a preferential solution of the present invention, the expander unitcomprises an expander male rotor and an expander female rotor, whereinthe liquid pump unit comprises a liquid pump male rotor and a liquidpump female rotor; an end of the expander male rotor is fixedlyconnected to the liquid pump male rotor, and the liquid pump male rotorrotates under driving of the expander male rotor.

As a preferential solution of the present invention, the shell comprisesan expander cavity and a liquid pump cavity isolated from each other;all or a main body part of the expander male rotor, and the expanderfemale rotor are disposed in the expander cavity; all or a main bodypart of the liquid pump male rotor, and the liquid pump female rotor aredisposed in the liquid pump cavity; an expander suction inlet, anexpander exhaust outlet, a liquid pump inlet and a liquid pump outletare disposed on the shell.

As a preferential solution of the present invention, the expander malerotor comprises a first rotor part and a first connection part which areintegrally designed; the first rotor part is disposed in the expandercavity and coordinates with the expander female rotor; the firstconnection part extends into the liquid pump male rotor in the liquidpump cavity.

As a preferential solution of the present invention, the liquid pumpmale rotor comprises a second rotor part and a second connection partwhich are integrally designed; the second rotor part is disposed in theliquid pump cavity and coordinates with the liquid pump female rotor;the second connection part extends into the expander male rotor in theexpander cavity.

As a preferential solution of the present invention, expander femalerotor bearings are separately disposed at two ends of the expanderfemale rotor, and liquid pump female rotor bearings are separatelydisposed at two ends of the liquid pump female rotor; a first male rotorbearing is disposed at an end of the expander male rotor away from theliquid pump male rotor; a second male rotor bearing is disposed at thefirst connection part and between the first rotor part of the expanderand the second rotor part of the liquid pump.

As a preferential solution of the present invention, the expander cavityand the liquid pump cavity are isolated from each other through anisolation mechanism, so that a hole is formed between the expandercavity and the liquid pump cavity; the first connection part passesthrough the hole and enters the liquid pump cavity.

The present invention has the following beneficial effects: in the ORCpower generation system and the liquid pump of the screw expanderthereof provided in the present invention, since a resistance torque ofthe liquid pump female rotor is very small, the liquid pump does notwear even when the liquid viscosity is very low, contributing to goodreliability. Meanwhile, the liquid pump is driven by the screw expander,thereby further improving power generation efficiency of the ORC. Inaddition, the semi-sealed or fully sealed shell can effectively preventleakage of the refrigerant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of composition of an ORC power generationsystem.

FIG. 2 is a schematic view of composition of an ORC power generationsystem using the present invention.

FIG. 3 is a sectional view of a liquid pump of a screw expander in avertical direction consistent with the present invention.

FIG. 4 is a sectional view of a liquid pump of a screw expander in ahorizontal direction consistent with the present invention.

LIST OF REFERENCE NUMERALS

1′ Expander

2′ Generator

3′ Evaporator

4′ Liquid pump

5′ Condenser

1 Expander

2 Generator

3 Evaporator

4 Liquid pump of a screw expander

5 Condenser

401 Expander male rotor

402 Expander female rotor

403 Liquid pump male rotor

404 Liquid pump female rotor

4051 First male rotor bearing

4052 Second male rotor bearing

4061 Expander female rotor bearing

4062 Expander female rotor bearing

4071 Liquid pump female rotor bearing

4072 Liquid pump female rotor bearing

408 Seal ring

409 Seal ring

410 Expander suction inlet

411 Expander exhaust outlet

412 Liquid pump inlet

413 Liquid pump outlet

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are described in detailwith reference to the accompanying drawings below.

Embodiment 1

Referring to FIG. 2, FIG. 2 shows an ORC power generation system usingthe present invention. The ORC power generation system includes acondenser 5, a liquid pump 4, an evaporator 3, an expander 1, and agenerator 2. The main improvement of the present invention consists inthe liquid pump 4. In this embodiment, the liquid pump 4 is a liquidpump 4 of a screw expander.

Specifically, referring to FIG. 3 and FIG. 4, the liquid pump 4 of ascrew expander includes a semi-sealed or fully sealed shell. The shellis formed of multiple components, and a seal ring 409 is disposed ateach gap between components. An expander suction inlet 410, an expanderexhaust outlet 411, a liquid pump inlet 412 and a liquid pump outlet 413are disposed on the shell. The expander suction inlet 410 and theexpander exhaust outlet 411 are respectively connected to an outlet ofthe evaporator 3 and an inlet of the condenser 5. The liquid pump inlet412 and the liquid pump outlet 413 are respectively connected to anoutlet of the condenser 5 and an inlet of the evaporator 3.

An expander unit and a liquid pump unit are disposed in the shell. Theexpander unit includes a screw rotor, and the liquid pump unit includesa screw rotor. The rotor of the expander unit is fixedly connected tothe rotor of the liquid pump unit. The rotor of the liquid pump unitrotates under driving of the rotor of the expander unit.

As shown in FIG. 4, the expander unit includes an expander male rotor401 and an expander female rotor 402. The liquid pump unit includes aliquid pump male rotor 403 and a liquid pump female rotor 404. An end ofthe expander male rotor 401 is fixedly connected to the liquid pump malerotor 403, and the liquid pump male rotor 403 rotates under driving ofthe expander male rotor 401.

The shell includes an expander cavity and a liquid pump cavity isolatedfrom each other. All or a main body part of the expander male rotor 401,and the expander female rotor 402 are disposed in the expander cavity.All or a main body part of the liquid pump male rotor 403, and theliquid pump female rotor 404 are disposed in the liquid pump cavity. Inthis embodiment, the expander male rotor 401 extends into the liquidpump male rotor 403 in the liquid pump cavity.

Further referring to FIG. 4, the expander male rotor 401 includes afirst rotor part and a first connection part which are integrallydesigned. The first rotor part is disposed in the expander cavity andcoordinates with the expander female rotor 402. The first connectionpart extends into the liquid pump male rotor 403 in the liquid pumpcavity.

Expander female rotor bearings 4061 and 4062 are separately disposed attwo ends of the expander female rotor 402. Liquid pump female rotorbearings 4071 and 4072 are separately disposed at two ends of the liquidpump female rotor 404. A first male rotor bearing 4051 is disposed at anend of the expander male rotor 401 away from the liquid pump male rotor403. A second male rotor bearing 4052 is disposed at the firstconnection part and between the first rotor part of the expander and thesecond rotor part of the liquid pump.

The expander cavity and the liquid pump cavity are isolated from eachother through an isolation mechanism, so that a hole is formed betweenthe expander cavity and the liquid pump cavity. The first connectionpart passes through the hole and enters the liquid pump cavity.

The seal ring 408 is used to seal and separate a rotor cavity (theliquid pump cavity) and a bearing cavity (the expander cavity), therebyensuring effective lubrication of the bearing.

In conclusion, in the liquid pump of a screw expander provided in thepresent invention, since a resistance torque of the liquid pump femalerotor is very small, the liquid pump does not wear even when the liquidviscosity is very low, contributing to good reliability. Meanwhile, theliquid pump is driven by the screw expander, thereby further improvingthe power generation efficiency of the ORC. In addition, the semi-sealedor fully sealed shell can effectively prevent leakage of therefrigerant.

Embodiment 2

This embodiment differs from Embodiment 1 in that, in this embodiment,the liquid pump male rotor extends into the expander male rotor.

Specifically, the liquid pump male rotor includes a second rotor partand a second connection part which are integrally designed. The secondrotor part is disposed in the liquid pump cavity and coordinates withthe liquid pump female rotor. The second connection part extends intothe expander male rotor in the expander cavity.

In addition, in the foregoing embodiments, both the expander unit andthe liquid pump unit include two screws. Definitely, the expander unitand the liquid pump unit may include other numbers of screws.

Herein, the description and application of the present invention areillustrative, and the scope of the present invention is not intended tobe limited to the above embodiments. Variations and changes to theembodiments disclosed herein are possible. Replacement made to theembodiments and equivalent parts are well-known to persons skilled inthe art. It should be known to persons skilled in the art that, thepresent invention can be implemented in other forms, structures,arrangements, ratios and through other components, materials, and partswithout departing from the script or essential features of the presentinvention. Other variations and changes may be made to the embodimentsdisclosed herein without departing from the scope and script of thepresent invention.

1. A liquid pump of a screw expander, comprising a semi-sealed or fullysealed shell, wherein an expander unit and a liquid pump unit aredisposed in the shell; the expander unit comprises a screw rotor, andthe liquid pump unit comprises a screw rotor; the rotor of the expanderunit is fixedly connected to the rotor of the liquid pump unit, and therotor of the liquid pump unit rotates under driving of the rotor of theexpander unit.
 2. The liquid pump of a screw expander as in claim 1,wherein the expander unit comprises an expander male rotor and anexpander female rotor, and the liquid pump unit comprises a liquid pumpmale rotor and a liquid pump female rotor; an end of the expander malerotor is fixedly connected to the liquid pump male rotor, and the liquidpump male rotor rotates under driving of the expander male rotor.
 3. Theliquid pump of a screw expander as in claim 2, wherein the shellcomprises an expander cavity and a liquid pump cavity isolated from eachother; all or a main body part of the expander male rotor, and theexpander female rotor are disposed in the expander cavity; and all or amain body part of the liquid pump male rotor, and the liquid pump femalerotor are disposed in the liquid pump cavity; an expander suction inlet,an expander exhaust outlet, a liquid pump inlet and a liquid pump outletare disposed on the shell.
 4. The liquid pump of a screw expander as inclaim 3, wherein the expander male rotor comprises a first rotor partand a first connection part which are integrally designed; the firstrotor part is disposed in the expander cavity and coordinates with theexpander female rotor; and the first connection part extends into theliquid pump male rotor in the liquid pump cavity.
 5. The liquid pump ofa screw expander as in claim 3, wherein the liquid pump male rotorcomprises a second rotor part and a second connection part which areintegrally designed; the second rotor part is disposed in the liquidpump cavity and coordinates with the liquid pump female rotor; and thesecond connection part extends into the expander male rotor in theexpander cavity.
 6. The liquid pump of a screw expander as in claim 4,wherein expander female rotor bearings are separately disposed at twoends of the expander female rotor, and liquid pump female rotor bearingsare separately disposed at two ends of the liquid pump female rotor; afirst male rotor bearing is disposed at an end of the expander malerotor away from the liquid pump male rotor, and a second male rotorbearing is disposed at the first connection part and between the firstrotor part of the expander and the second rotor part of the liquid pump.7. The liquid pump of a screw expander as in claim 6, wherein theexpander cavity and the liquid pump cavity are isolated from each otherthrough an isolation mechanism, so that a hole is formed between theexpander cavity and the liquid pump cavity, and the first connectionpart passes through the hole and enters the liquid pump cavity.
 8. Aliquid pump of a screw expander, applied to an Organic Rankin Cycle(ORC), comprising a semi-sealed or fully sealed shell, wherein anexpander male rotor, an expander female rotor, a liquid pump male rotorand a liquid pump female rotor are disposed in the shell; an end of theexpander male rotor is fixedly connected to the liquid pump male rotor,and the liquid pump male rotor rotates under driving of the expandermale rotor; the shell comprises an expander cavity and a liquid pumpcavity isolated from each other; all or a main body part of the expandermale rotor, and the expander female rotor are disposed in the expandercavity; all or a main body part of the liquid pump male rotor, and theliquid pump female rotor are disposed in the liquid pump cavity; anexpander suction inlet, an expander exhaust outlet, a liquid pump inletand a liquid pump outlet are disposed on the shell; the expander malerotor comprises a first rotor part and a first connection part which areintegrally designed; the first rotor part is disposed in the expandercavity and coordinates with the expander female rotor; and the firstconnection part extends into the liquid pump male rotor in the liquidpump cavity; expander female rotor bearings are separately disposed attwo ends of the expander female rotor, and liquid pump female rotorbearings are separately disposed at two ends of the liquid pump femalerotor; a first male rotor bearing is disposed at an end of the expandermale rotor away from the liquid pump male rotor; a second male rotorbearing is disposed at the first connection part and between the firstrotor part of the expander and the second rotor part of the liquid pump;and the expander cavity and the liquid pump cavity are isolated fromeach other through an isolation mechanism, so that a hole is formedbetween the expander cavity and the liquid pump cavity, and the firstconnection part passes through the hole and enters the liquid pumpcavity